This invention is directed to devices for the treatment of constricted ducts in human bodies. More particularly, this invention is directed to temporary intravascular, urethral, ureteral, bronchial, oesophageal, and biliary stent systems.
Coronary angioplasty has gained wide acceptance as a routine management of coronary stenosis. The technique of the procedure and the manufacture of balloons has improved over the years; however, in spite of such improvements, acute coronary occlusion of a coronary artery, which accounts for about 6% of the cases, continues to be a major concern. Despite improvements in technology and experience, it is still difficult to predict the occurrence of this critical complication.
Accordingly, there is a serious need for treatment for acute occlusions. Several treatment modalities, such as long balloon inflations with the use of a perfusion balloon, laser balloon angioplasty, and, more recently, a temporary stent, have been suggested. However, when such measures fail or become less effective, the patient may require emergency coronary bypass surgery, with which an increased rate of morbidity and mortality is associated.
Temporary stents have been suggested as a method to apply radial force on the occluded segment, thus facilitating free blood flow through the artery to the muscle and tissue at that time. If prolonged radial force is applied, perhaps for up to a few hours or days, then vessel closure may reverse. Possible mechanisms of such reversal are that a dissection flap is tacked to the vessel wall, or that elastic recoil occurs, such as during the first few hours after PTCA is performed.
Despite the theoretical advantage of a temporary stent, there are problems in providing a stent that is readily removable and at the same time easy to insert, flexible, and safe. Most of the known stents intended for coronary and peripheral artery use are not readily removable and require arduous removal techniques or surgical intervention.
The present invention relates to a device intended for use in dealing with constrictions in ducts of the human body to relieve the possible pathological results of such stenoses. The invention comprises a stent that is configured to be readily removable upon demand from a constricted duct. The temporary stent is to be used in those instances wherein having the stent in position within the constricted duct for a period of from an hour or more to several days is believed to have a positive clinical effect.
It is an object of this invention to provide a device for the treatment of constricted ducts in human bodies, such as arteries, urethras, ureters, biliary tracts, and the like.
It is also an object of this invention to provide a temporary stent capable of readily, non-traumatic removal from the patient.